It's not Rick. He's the leader. Negan needs Rick to steer his people in to working for him.
Plus, it would just be too big of a deviation from the books. Rick is THE main character. It's not him. Not that I disagree with anything you're saying. It's just not happening. If Rick ever dies, which I doubt, it will either be because the show is ending or the ratings are so badly in the tank that they need to do something majorly major.
It should be Glenn or Daryl. Either of those would make the maximum impact, which is the point of all this. Abraham of Eugene would not accomplish that.
Oh, and I'm really pissed about the cliffhanger too. They built up to this moment all season and didn't really deliver. Negan was great and all, but this wasn't satisfying at all.